Tree Surveys & Site Safety

I have re-opened the poll for aspects of arboriculture that people are interested in learning more about. Tree biology is still the hot favourite however today I am posting about tree management.

My sister recently asked if she could come out on site with me and bring my nephew so they could better understand what I do for a living. I of course said yes as I love spending time with them both, talking about trees and I am always trying to coax youngsters into the industry!

I have recently been involved with a school group using a woodland I manage as an outdoor classroom and had an opportunity to talk to the group of children aged between 8-9 about trees and some of the really interesting things about them. It was a very rewarding experience and they bombarded me with great questions.

Anyway, I started thinking about my family being on site with me and the best sites to take them to which made me reassess the safety of my working environment so I thought I would post about my role as a tree inspector and cover the safety aspects of that role, and what I do for tree inspections.

I am always aware of the hazards however for myself they are a part of my job that I am used to being aware of and I act accordingly on site instinctively. As a result I am going to visit a non work related public site with my family so that we may take the time to go through inspecting trees without the hazards involved in my daily job.

Site Hazards

The first and most obvious hazard is that I work with trees that can be very large and in a poor condition, I therefore am responsible for assessing the safety of the tree from a distance and then as I get closer before I even start taking measurements and making notes.

Trees may have hanging branches, loose deadwood or be unstable and it is obviously important to ascertain that before I start.

There is also livestock to be aware of, they are generally not dangerous however it is always good to know if they are there and where exactly they are. Being surprised by a bull is not fun, for either of you!

Many of the sites I visit have access constraints either to keep people out or keep livestock or people in! I am pretty deft at climbing a variety of fences with minimal personal harm however I of course carry a first aid kit with me at all times.

There are also numerous safety issues throughout the sites I visit at ground level. Animal waste is a big issue, I usually wear rigger boots which in addition to the steel protection for my feet protect the bottom of my clothes so if I do tread in something it stays on my shoes only. The rigger boots are a personal choice and have shielded my feet from many a nail.

Site maintenance work is common however many jobs seem to be left unfinished and grass grows quickly. There are often uncovered drains and inspection chambers, collapsed utility cables which may or may not be live, curb stones and pitted hard standing, in addition to badger setts, rabbit burrows, areas of bog, deep water!

Site traffic or traffic on adjacent highways is also an issue. Not being on the road does not guarantee that you are out of danger. A colleague of mine was nearly hit by a car loosing control on a highway adjacent to the site he was working on.

The car finished up metres away from where he was surveying however he was paying close attention to the adjacent hazard and managed to move out of the way in good time.

There is also the lone working aspect of my job and I am frequently in remote areas however my company operates an excellent lone working policy which gives me assurance. In addition I often take my two German Shepherds with me and no one is getting anywhere near me with them around!

Linked to this issue is the matter of the public who can respond in a variety of ways when they encounter you. Many people are scared about coming across someone wondering around, I have been accused of many things on site especially when I have my hammer in my hand! Some people are very friendly and like to chat to you about trees, often dog walkers who tend to be out and about enjoying the countryside with their dogs. There is the occasional odd looking person and groups of people enjoying themselves with fires and beers are also best to be avoided. In my experience people out enjoying them selves are rarely a threat and usually very approachable however due to the lone working environment it is best not to take that risk.

And there is finally a small percentage of people who will be annoyed with you for a number of reasons: some suspect you are planning to remove the trees and don't want you too, some want the trees to be removed as they don't want them there, some suspect you are going to build on the site and have strong feelings about that, some assume you work for the council and want to complain about their taxes or the bin collections, some think they have a right to camp on the site and do not like to be approached or spoken to, once you have identified yourself as someone involved in the site management you can instantly become public enemy number one and their reaction to you can be volatile.

It is best to go to site with your own safety foremost in your mind, avoid contact with the public where possible and report issues out of your control to the appropriate department.

We employ security staff to deal with trespassers. They are usually teams of men used to dealing with aggressive people and are appropriately trained for any eventuality. I am not!

Tree Surveys

Following the initial assessment of the site you are working on tree surveying may commence.

There are different types of tree surveys which are dependant on the clients needs and the trees proximity to areas of public usage or utilities.

Most commonly I perform full tree condition surveys which involves me mapping the trees location on a site plan and recording full data regarding their size and condition.

We record the following data for tree identification and condition assessment:

Species, height, stem girth, age class. All trees have a potential size and form specific to their species. They are however also subject to the stimulus of their environment which has an impact on their growth habits. This is an important factor to consider when purchasing trees for planting. It is vital that you are aware of how big they can get and what the form of their crowns is likely to be in maturity.

I have seen many examples of large trees planted in small front gardens which will cause severe issues for the residents who are living there when the trees reach maturity. The favourite for this seems to be Monkey Puzzle trees, Araucaria araucana.

These trees have very attractive and interesting foliage and I often see them for sale at nurseries in among the shrubs with no information about their ultimate size, nor the size of the cones they produce.

Following measurement of a tree we record its structural form and condition. This relates to stem and branch form which may be multi stemmed or single stemmed and includes comments regarding the condition of main branch unions.

My post An Introduction to Tree Biology - How Trees Grow #1 included comments and pictures of trees with tight stem unions that predispose the to structural failure.

The physiological condition of the tree is then assessed from branch tip to root collar. The inspection is made to assess for branch die back which can be indicative of root damage or root and stem disease.

See An Introduction to Tree Biology - Root I & II

The assessment also looks for deadwood, which can also be attributed to root damage or root and stem issues, damaged branches, cracks and splits in branches which may be significant in terms of required tree care or may provide habitat for bats and birds, evidence of any damage to the crown of the tree or evidence of any pests and diseases. Evidence of previous tree management, and development of cavities and/ or decay which can occur at pruning wounds and are noted if significant, any signs of habitat within the tree such as woodpecker holes or bird nests which are always recorded, and the shape and form of the crown which may indicate significant site issues such as prevailing winds or competition for light from adjacent cover or structures.

The foliage of a tree is also assessed in addition to it's annual branch extension growth. The colour of a trees leaves can indicate poor tree health as well as being the site for numerous pests, and extension growth can give an indication of the trees health in this and previous growing seasons.

Once a full assessment of the crown and branches of a tree have been made the stem and root collar are inspected for associated defects such as fibre buckling, cracks and splits, loose or necrotic bark which may be evidence of previous wounding or disease, and any other symptoms of issues such as swelling of the stem, the fruiting bodies of fungus which may or may not be significant.

The ground around the tree is also assessed to check for fungal fruiting bodies, surface roots and possible damage to them, signs of root plate movement, and the condition of the soil or medium the tree is growing in.

Comments are recorded for any significant defects noted with management prescriptions made to remedy any such issues or specify further investigation which may take the form of a climbing inspection, soil testing or even decay detection by means of appropriate equipment.

The environment for each tree is also commented on where significant factors are noted such as livestock razing or ploughing which can be very detrimental to trees, or site hazards which can be significant to any required management such as adjacent structures, areas of public usage or utilities.

There is other data collected during other types of tree inspections such as a pre-development site tree surveys in keeping with British Standard 5837 - Trees in Relation to Construction however this type of survey will be discussed in a separate post.

The number of trees inspected within one working day is site specific however it is possible to inspect between 150-200 trees within an 8 hour period however you have to shift a bit!

Image Credit for Monkey Puzzle Images: The Royal Botanic Garden of Edinburgh Lets Go Gardening and My Blue Muse

Tree Planting

The best part of my job is planting trees. It is very hard to convince people to invest in looking after their old trees. Similarly it is hard to get landowners to invest in tree planting and appropriate aftercare to support their survival however many of the mature trees we see and appreciate today were planted by someone, had they not taken the time and the effort what would we have?

These species are some of the trees I have planned for a restoration project during this autumn and winter.



I usually buy containerised trees and will be going to the nursery in July to pick out the specific trees I want.



The nursery are very good however if you leave it until they arrive on site it is difficult to go through them all and make sure there are no issues. Also when you are spending between £80 - £200 on a tree you want to make sure its the best of the bunch.



I went to one of the formal parks I manage yesterday to look at some trees that have been vandalised. They will need to be replaced in the autumn.

While I was there I took some pictures of the trees that have been establishing at the park. Some of these species I will be planting at other sites later in the year. The species shown here in order of appearance are: Giant Redwood or Wellingtonia (Sequoiadendron giganteum), Deodar Cedar (Cedrus deodara), Blue Atlantic Cedar or Blue Atlas Cedar(Cedrus artlantica 'Glauca') and Giant Redwood again (Sequioadendron giganteum).

Tree planting is, as I have mentioned, the best part of my job and I am looking forward to getting the trees in and watching them develop in the coming years. I will not see them develop into maturity however if other people had not planted trees throughout the last few centuries I would not get to enjoy the mature treescapes I get to walk through. It is a legacy for the future.

Veteran Oak Pollards

I came across these veteran oak pollards in London. They are several hundred years old and I was delighted to see that when the housing estate had been built around them they had made some effort to provide the trees with a suitable growing environment. It is sadly not sufficient however by comparison with some sites it is generous.

Unfortunately trees often suffer during development despite there being guidelines to afford them, and in particular their root systems, protection. In the next post I will start on tree management and in particular trees in relation to development.

An Introduction to Tree Biology: How Trees Grow # 1

Understanding how trees grow enables us to better care for them throughout their lives.

Trees do not grow from the bottom up, continuing to push from the bottom of their stems, rather they elongate from their shoot tips and expand around their circumference by generating new cells annually.

The end of every shoot contains an area termed a meristem which develops new growth each year. This new growth is called extension growth. New layers of cells are developed at the end of an existing shoot.

The length of the extension growth in any one year is a result of the trees available energy and therefore can give an indication of the trees health. Extension growth may vary from year to year dependant on available energy however, in a healthy tree would appear uniform from year to year.

This picture (Picture 1 - Extension Growth) shows the extension growth on a Rowan tree (Sorbus commixta 'Embley'). The rings around the shoot at the bottom of the picture are the terminal or apical bud scale scar.

In other words this is where the tree grew to last year and marks the start of this years extension growth. (The terminal bud scale scar is not so obvious on all tree species however on rowan and cherry trees it is particularly easy to observe.)

As this is occurring another meristematic area beneath the bark of existing shoots, branches, and the main stem, develops new growth to provide an annual increase in the width of a tree, and its branches.

Therefore at the same time that the tree is growing taller by production of annual extension growth it is growing wider by production of annual tree rings. These are the rings that can be counted in the cross section of a felled tree from which people calculate tree ages.

When observing a young tree predictions can be made regarding its form in maturity from it’s existing branch structure.

This picture (Picture 2 - Beech Union) of a beech tree shows a co-dominant branch union, where two branches have developed almost at the same time and are therefore of a similar size.

The branches would have started growing with an acute angle between them indicating that in maturity, through the development of annual ring growth around the circumference of each branch, the branches would eventually come into contact with each other.

Tight unions can be structural defects occurring in stems, branches and shoots, and can be susceptible to failure. In the instance of the beech tree, in Picture 2, as the branches continue to develop growth around their circumference they push against each other and the result may be failure of one of the branches or splitting of the union.

The union in this Goat Willow (Picture 3 - Willow Union) has split and although the tree has managed to remain intact the split has progressed down the main stem and the tree is predisposed to failure. (There is another defect associated with tight unions termed included bark which will be discussed at a later date. Not all tight unions develop included bark.)

In a young tree identification of such defects means they can easily be remedied. In the instance of the beech tree (Picture 2) one of the branches could have been removed when the tree was young by means of secatuers resulting in a small wound that would have quickly callused over promoting the remaining branch as the lead stem of the tree.

As you can see it would be extremely difficult to remove one of these branches now and the resultant wound would be much larger and significant in terms of wounding.

Identifying growth and structural defects in young trees and affecting the necessary pruning to remedy them is termed formative pruning.

Formative pruning should be undertaken at the nursery stage. It is something to be aware of when purchasing trees. If formative pruning is undertaken it can negate the requirement for significant and costly tree pruning at a later date or prevent tree or branch failure.

It is important that if you have any concerns regarding the form or condition of your tree/s you seek professional advice from a qualified arboricultural consultant. They usually offer advice for free and will be able to advise you whether further investigation is required and what if any remedial actions you should or can undertake in order to address your concerns.

They will also be able to recommend a good arboricultural contractor to undertake any proposed tree works. Contractors are not all consultants and tree works and tree consultancy should be treated as separate areas of expertise. N.B. Many arboricultural contractors have a good consultancy knowledge however this should not be assumed.

Ginkgo biloba - The Maidenhair Tree

An Introduction to Tree Biology: Roots II

As tree biology seems to be a favourite I have decided to pick things up there with another post about tree roots, such a very vital part of a tree. To view the first post regarding tree roots click here.

We have recently purchased two new trees for our garden. The trees were pot planted however have been in the nursery for some time and as a result the root system had persisted through the drainage holes in the pot and into the surrounding soil and gravel.

We asked an assistant to help us with freeing the trees and she kindly provided secateurs and a strong hand to support the trees while we freed the roots. Her initial response had been to simply pull the trees free however this would have been disastrous and snapped most of the roots off. With a small amount of effort we were able to unearth the existing roots and prune any larger roots that could not be freed.

As previously discussed the finer string like fibrous roots provide water and nutrient uptake, without them the tree struggles to feed itself until new feeder roots can be established. The larger roots in addition to providing anchorage are storage facilities for sugars termed photosynthates produced by means of photosynthesis. These photosynthates are the energy providing material for the tree and are utilised to achieve growth and defense amongst other functions.

Planting should ideally be undertaken within the dormant season i.e. autumn and winter thus allowing trees to recover from transplant shock and begin establishment of their root system within the new area of soil usually moist due to the environmental conditions at this time of year.

Trees can be planted during the spring and summer however will almost undoubtedly require watering to prevent drought stress.

Upon planting, the tree root system should be spread evenly around the planting pit having loosened up the sides of the planting pit walls to allow easier root penetration into the soil. Trees grown in containers often develop what is termed girdled root which occurs when tree roots develop to the extents of their container and as they continue growing begin to circle the container. Any such barrier that a tree encounters in early root development may result in girdled root.

Trees planted with girdled roots can in some cases suffer stem failure later in life as a result of the girdled root exerting pressure against the main stem and vice verse as they put on their annual growth and increase in girth.

The reason that so much care is required when dealing with trees, and such a delicate and complex component as roots, is that trees have a finite amount of energy available to them. If this energy is utilised inappropriately due to unnecessary wounding or other actions the energy already ring fenced for normal annual operations is not available and trees begin to decline.

For example a tree planted carelessly during winter that is required to utilise stored energy for root repair or re-development will have less energy available to produce it's leaves in the spring. As a result the leaves may be undersized and therefore have a smaller surface area to photosynthesise during the summer months. This results is a lesser yield of photosynthates during the summer and the cycle continues.

Similarly if fertiliser or other organic matter is applied to a tree when it is not required the tree will still utilise the available food to it's own detriment. The increased food levels will stimulate growth in excess of normal levels. As every function of a tree uses energy this forced growth takes energy away which is required for another process.

Depleted energy reserves make a tree more at risk from pests and diseases as it is less able to instigate it's defense systems.

If sever drought stress occurs the parts of a tree responsible for photosynthesis can be damaged permanently resulting in a photosynthetic disability for the remainder of that trees life.

Trees can recover from small levels of stress over a period of time however an accumulation of stress can lead to decline and premature death. An excess of stress is termed strain.

It should be noted that trees are very good at looking after themselves without any of our assistance however when we start to place trees in demanding situations such as urban planting there are precautionary measures that can be taken to ensure the best environment for the tree is achieved. Appropriate ground preparation and consideration of a developing root system and it's specific needs is vital.

If you have any questions about this or any other post please feel free to leave me a comment and I will do my best to answer your query.

Trees & Related Ecology

Trees and related ecology is the hot favourite on the tree topic poll at present so I am going to do a post covering the most obvious species associated with trees, birds.



Image Credit: Poppy 1812

Birds use trees for food, shelter, nesting, beak cleaning, broad casting their mating calls and probably a few other reasons I have not mentioned here! The bigger the tree the better the habitat.

Trees in urban areas are often reduced in height to address peoples concerns. Common issues are volume of leaf litter, a lack of day light, and to alleviate their fears regarding the safety of tall trees. Trees bend in the wind to distribute the forces acting upon them. This swaying can be extreme and usually causes unwarranted concern.



Image Credit: Nancifi

It is widely recognised that when urban trees are reduced greatly in height, or in areas where smaller trees replace larger historic planting, an increase in predator birds such as the magpie is seen in conjunction with a reduction in song birds.

The bigger the tree, the greater number and variety of birds.



Image Credit: Chuck4Photos

It should be noted that we have many ground vegetation and hedgerow nesting birds in this country, and all birds and their nests are protected by Statute Law in The Wildlife and Countryside Act 1981.

'The Act makes it an offence (with exception to species listed in Schedule 2) to intentionally kill, injure, or take any wild bird or their eggs or nests. Special penalties are available for offences related to birds listed on Schedule 1, for which there are additional offences of disturbing these birds at their nests, or their dependent young. The Secretary of State may also designate Areas of Special Protection (subject to exceptions) to provide further protection to birds. The Act also prohibits certain methods of killing, injuring, or taking birds, restricts the sale and possession of captive bred birds, and sets standards for keeping birds in captivity..

Text Credit: Joint Nature Conservation Commitee



Image Credit: MeAbbott

Tree works are often disturbed or delayed due to nesting birds however it is part of tree management and there are many ecological concerns in arboriculture.

Just to touch on tree management while I have mentioned the subject, there are several times of year where tree works are problematic, or detrimental to the tree, not all of which coincide with sensitive times for associated ecological species. I will cover this in more detail within tree biology and tree management.

Poll Response

I am delighted that there has been so much interest in the tree poll and will begin posting about topics you have expressed an interest in. I have been thinking about how to approach it and have decided that once a month I will do a post related to the poll.

I will start with the most popular topic, which currently seems to be related ecology, and cover the rest in turn.

Thank you to every one who voted. Arboriculture is my profession, and a passion I am happy to share. More soon!

The Tallest Tree in the UK......maybe

This is believed to be the tallest tree in the UK although I know it is competition with a similar tree in Wales. This is a Douglas Fir, Pseudotsuga menziesii, and stands at a whopping 65m!

Its the one in the middle! It was a little hard to get a good shot of this tree as it is in a woodland, beside a river!

Tyger Tyger

This tree lost it's leading stem at an early age which stimulated two side shoots to seek 'apical dominance' and replace the lost leading shoot. This tree managed to accomplish this with perfect symmetry.